Water discrimination fuze



Aug. 25, 1959 H. D. SAUNDERSON WATER DISCRIMINATION FUZE Filed March 15,1956 3 Sheets-Sheet 1 FIG. I

FIG. 2

INVENTOR.

H. D. SAUNDERSON ATTORNEYS g- 1959 H. D. SAUNDERSON 2,900,912

WATER DISCRIMINATION FUZE FiledMarch 15, 1956 3 Sheets-Sheet 2 FIG.4

' INVENTOR.

H. D. SAUNDERSON ATTORNEYS Aug. 25, 1959 Filed March 15, 1956 DRAGDECELERATION (g) ENTRY DECELERATION (9 H. D. SAUNDERSON WATER mscammuzonFUZE 3 sheets -sheet :s

FIG. 5 60 ENTRY VELOC|TY (feet per second) 80 so F|G.6 40

0 0| 0.2 0.3 0.4 0.5 TIME AFTER ENTRY (seconds) INVENTOR.

ATTORNEYS United States Patent WATER DISCRIMINATION FUZE Henry D.Saunderson, Riverside, Calif., assignor to the United States of Americaas represented by the Secretary of the Navy Application March 15, 1956,Serial No. 571,851

3 Claims. (Cl. 102-76) (Granted under Title 35, US. Code (1952), see.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to a fuze and more particularly to a waterdiscrimination fuze which prepares a detonator within the fuze of amissile in response to the deceleration of the missile as it changesfrom a relatively high velocity in air to a much lower velocity inwater.

Prior to this invention direct mechanical means have been utilizedeither manually or automatically actuated prior to or at the moment ofrelease of a missile or alternatively by means of a timing device or awater flow meter after release. These devices were complex and subjectto human failure and moreover were subject to mechanical failure.

Various missiles have a normal course that consists of an air flightfollowed by entry into water and a subsequent run under the surface ofthe water. It is desirable to prepare the detonator within the fuze ofsuch a missile so as to arm the missile after it has entered the water.It is also desirable that such a missile not be armed by the normal andaccidental shock forces that are encountered during handling andshipping, and that the fuze be simple, compact, and completely enclosedor sealed within the missile.

The water discrimination fuze of the present invention prepares thedetonator within the fuze of a missile in response to the decelerationof the missile as it changes from a relatively high velocity in air to amuch lower velocity in water.

One preferred embodiment of the present invention utilizes the inertiaof a number of spring restrained masses that move sequentially as themissile is decelerated to unlatch a detonator carrying rotor which,after completion of its movement, causes mechanical alignment of thedetonator with a charge within the missile and also closes electriccontacts to arm the missile.

One object of the present invention is to provide a missile fuzingsystem which will not be actuated until after water entry.

Another object of the present invention is to provide a waterdiscrimination fuze which will not be armed by the normal or accidentalshock forces that are encountered during handling and shipping.

A still further object of the present invention is to provide a fuzewhich will only arm subsequent to the typical deceleration encounteredby an air flight missile when it enters the water prior to a run underthe surface of the water.

A still further object of the present invention is to provide a waterdiscrimination f-uze which is simple, compact, and completely enclosedor sealed within the missile.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is a pictorial view of one preferred embodiment of the presentinvention taken nearly normal to the direction of flight of the Waterdiscrimination fuze within a .missile and with the arrow indicating thedirection of flight of the missile;

Fig. 2 is a plan view of the fuze illustrated in Fig. 1 taken in thedirection of flight if it were mounted within a missile;

Fig. 3 is an enlarged fragmentary cross-sectional view taken on line 33of Fig. 2 showing two alternate leaves with their restoring springs andillustrating by phantom lines the unlatching of the second leaf bymovement of the first leaf in response to inertial forces;

Fig. 4 is an enlarged view showing a pair of alternate leaves having asomewhat different shape but functioning in the same manner as theleaves of Fig. 3;

Fig. 5 is a graph showing the entry or initial deceleration with regardto the velocity of the missile such as a torpedo as it leaves the airand enters the water; and

Fig. 6 is a graph showing the relationship between time and decelerationof a missile such as a torpedo which has a specific entry velocity afterit enters the water.

Referring now to Fig. 5, the entry deceleration of a specific missile,such as a torpedo, is given in terms of the entry velocity as themissile leaves the air and enters the water. After submergence, waterdrag continues to decelerate the missile, as shown in Fig. 6 for aspecific missile having an entry velocity of 500 ft./sec., until it hasa velocity determined by its prime mover. It will be seen from thesecurves that the overall deceleration of a missile, such as a torpedo,may vary from more than to more than 5 times the acceleration due togravity, as the velocity of the missile changes from a constant airflight velocity to a constant underwater velocity. Missile decelerationwithin the order of these magnitudes that extend over a predeterminedtime interval are required to prepare the water discrimination fuze ofthis invention to arm a missile and, therefore, shocks normallyencountered during handling and shipping or accidental shocks do notprepare the detonator within the fuze.

One preferred embodiment of the fuze of the present invention shown inFigs. 1 through 3 in which the supporting frame 10 has secured theretoplates 11 and 12 machined at one end to form bearings with caps 13 and14 and bridged by an electric contact-carrying member 15 rigidlyfastened to the plates 11 and 12. A rotor 17 is rotatably mounted on ashaft 16 and has a hole 18 located at right angles to the axis ofrotation in which a detonator is placed. Electric connections from sucha detonator are made to terminate at a ground connection on the rotorand at a contact terminal 19 insulated from the rotor. One end of coilspring 20 is fixed to plate 12 and the other end of coil spring 20 isfixed to the extension of shaft 16. Detent pin 21 is mounted in the sideof rotor 17.

Also secured to supporting frame 10 is a U-shaped bracket 22 through theside members of which rigidly secured shafts or pivots 23 and 24 carry agroup of leaves 25, rotatable on pivot 23, and a group of leaves 26,rotatable on pivot 24. Each leaf 26 is rotatably mounted by a bearing 27on pivot 24, as shown in Fig. 3, and has a pivot clearance slot 28, and,except for outermost leaf 25, a detent pin 29. Similarly, as shown inFig. 3, each leaf 25 is rotatably mounted by a bearing on pivot 23 andhas a pivot clearance slot (not shown) and a detent pin 31. Restrainingsprings 32 are secured to the base of bracket 22 and act on the edgesurfaces of alternately mounted leaves 25 and 26 tending to restore themto a normal position, where pivot clearance slots such as 28 in contactwith pivots 23 and 24 serve as stops, as shown in Fig. 3 in phantomlines. Detent pins 29 and 31 rest on flat portions of the edges ofleaves 25 and 26, each preventing rotation of its leaf until the nextoutermost leaf has previously been rotated. Bracket 22 and innermostleaf 25 are mounted so that detent pin 21 in the side of rotor 17 restson the upper edge of innermost leaf 25 when in a normal position tolatch rotor 17.

Operation In the operation of the fuze the detonator-carrying rotor 17is first latched by rotating leaves 25 and 26 in sequence from theoutermost to the innermost leaf against the force of springs 32 and thenrotating rotor 17 against coil spring 20 until detent pin 21 clears andthen rests on the edge of innermost leaf 25. The leaves 25 and 26 arethen released in sequence from the innermost to the outermost leaf totheir normal positions. With rotor 17 in latched position, as shown inFig. 1, the detonator (not shown) adapted to be placed in hole 18 is notin mechanical alignment with the charge within the missile andaccidental detonation cannot fire the charge. Electric contact terminal19 is also displaced from the electric contact 33 on member 15 so thatautomatic or mechanical closure of a firing switch, connected in aseries circuit with a source of electric power, the contacts 19 and 33,and leads terminating in the detonater, cannot ignite the detonatorwhile rotor 17 is latched.

When a missile with rotor 17 of its fuze latched leaves its air flightand enters water, a large entry deceleration of the missile takes place,as shown in Figs. and 6. Since leaves 25 and 26 consist ofspring-restrained and inertia-responsive masses all of the leaves willtend to move, but only outermost leaf 25 is free to rotate about itsbearing 27 to a position where detent pin 31 is free to move which willunlatch adjacent leaf 26. Adjacent leaf 26 is now free to rotate, asillustrated by phantom lines in Fig. 3, provided deceleration of themissile continues and the inertial forces acting on the mass of leaf 26exceed the restoring force of its restraining spring 32. It will benoted that for leaves 25 and 26 of equal masses and similar restrainingsprings 32, decrease in decelerations of the missile requirecorrespondingly longer intervals for each leaf to move a given distanceto unlatch the adjacent leaf. However this might result in too rapidresponse to high inertial forces at entry or no response to the smallerforces as the missile approaches its normal water velocity. Therefore itis usually necessary to vary the mass of leaves 25 and 26 and/or therestoring force of springs 32 to provide a step function which willapproach the curve of Fig. 6. If deceleration of the supporting framecontinues due to water drag, successive leaves 25, 26 rotate insequence, depending on the magnitude of their masses and on therestoring forces of springs 32, until detent pin 21 is free to move andunlatches rotor 17, which after rotation, mechanically aligns thedetonator in hole 18 with the charge in the missile to align theexplosive train and arm the fuze mechanically and also closes electriccontact 33 on member with contact terminal 19 on rotor 17 to arm thefuze in the missile electrically.

If the magnitude of deceleration of supporting frame 10 is sufiicient inmagnitude but not of proper duration to cause sequential rotation of allleaves and 26, rotor 17 will not unlatch, leaves 25 and 26 which haveunlatched will return to normal, and the missile will not be armed.

Alternate forms of leaves 34 and 35 are shown in Fig. 4 to illustratethe infinite variety of shapes and arrangements which will function inthe device of the present invention. The leaves 34 and 35 are rotatableon pivots 36 and 37 and have detent pins 38 and 39 respectively. Asomewhat longer slot 40 is shown to limit the movement of the leaves.

A subsequent improvement of the Water discrimination fuze of the presentinvention is disclosed in the patent applications of H. D. Saundersonfor Water Discriminating Fuze, Serial No. 405,264, filed January 20,1954.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. A water discrimination fuze comprising a rotor adapted for limitedrotational movement about an axis, said rotor having an aperture adaptedto receive a detonator and an electrical contact terminal, a pluralityof leaves eccentrically mounted for movement by the deceleration forcesresulting from entry of a missile into water, a pair of pivot pins formounting said leaves, each of said leaves having a slot therethrough,alternate leaves being mounted on one of said pivot pins and theintermediate leaves being mounted on the other pivot pin with said pivotpins extending through the slot in the leaves which are not mountedthereon, spring restraining means adapted to engage said leaves andresist movement due to deceleration, the first of said leaves being freeto move against said spring means when the missile is decelerated bywater entry, the other of said leaves having latching means adapted toengage the next preceding leaf until said leaf has moved against theaction of said spring means whereby said leaves are successively free tomove under the forces of sustained deceleration, and means on said rotorengaging the last of said leaves and adapted to be disengaged when saidleaf has moved under the forces of deceleration, and means adapted tomove said rotor when released to a position where said fuze is armedmechanically and electrically.

2. A water discrimination fuze comprising a rotor adapted for limitedrotational movement about an axis, said rotor having an aperture adaptedto receive a detonator and an electrical contact terminal, a pluralityof leaves eccentrically mounted for movement by the deceleration forcesresulting from entry of a missile into water, a pair of pivot pins formounting said leaves, each of said leaves having a slot therethrough,alternate leaves being mounted on one of said pivot pins and theintermediate leaves being mounted on the other pivot pin with said pivotpins extending through the slot in the leaves which are not mountedthereon, spring restraining means adapted to engage said leaves andresist movement due to deceleration, the first of said leaves being freeto move against said spring means when the missile is decelerated bywater entry, the other of said leaves having detent pins adapted toengage the next preceding leaf until said leaf has moved against theaction of said spring means whereby said leaves are successively free tomove under the forces of sustained deceleration, and a detent pin onsaid rotor engaging the last of said leaves and adapted to be disengagedwhen said leaf has moved under the forces of deceleration, and springmeans adapted to move said rotor when released to a position where saidfuze is armed mechanically and electrically.

3. In a shell fuze, a fuze body having a recess therein to receive arotor, a rotor mounted in said recess and movable from a position inwhich said rotor is in fuze disarming condition to a position in whichsaid fuze is armed, means for exerting a steady force for rotating saidrotor from disarmed to armed position, a first latching plate pivotallymounted in position for latching said rotor against movement fromdisarmed to armed position, said latching plate having an outer endengaged with a stud secured to said rotor in position to prevent pivotalmovement of said latching plate in response to exertion of said steadyforce, and said latching plate having a preponderance of mass located toexert a pivotal force to cause release of said outer end from said stud,upon development of a predetermined inertial force thereupon, and asecond latching plate overlying the said first latching plate, saidfirst latching plate having a stud projecting from a 5 6 face thereofinto latching engagement with a surface of References Cited in the fileof this patent said second latching plate, said second latching platebeing also pivotally mounted and being yieldingly biassed into UNITEDSTATES PATENTS latching position and having its mass distributed tocause 2,486,362 OBrien Oct. 25, 1949 pivotal movement to releasingposition, upon develop- 5 2,511,872 Parker June 20, 1950 ment of apredetermined inertial force thereupon. 2,586,437 Rabinow Feb. 19, 1952

